I regret to start by telling you this probably isn't what you want
to hear. I think you're probably considering a great way to turn some
fine rough into scrap. If you really want to use a Dremel for this
purpose, at least practice on some cheap "throw away" rough.
If your Dremel is like mine, it has a motor in it and is running on
110v AC Power. Grinding stone, especially something as hard as
quartz, requires a constant flow of water. The two are not usually a
pleasant combination. A flexible shaft type arrangement would be
better. My recommendation would be to keep the material until you can
save up to buy the proper equipment.
That being said, it is theoretically possible to cut a flat
surface with a small round wheel, like that used on a Dremel or
Foredom. However, an experienced lapidary (gem cutter) would be quick
to tell you it is very difficult. Faceters use flat "laps", thus the
term "lapping" for grinding a flat surface.
Assuming for the moment that you were to undertake such an endeavor,
you would want diamond (preferably), or silicon carbide tools for
your Dremel. Silicon carbide, being much the same hardness as quartz
(i.e., ametrine) would be a "hard row to hoe." Understanding the
relative hardness of minerals is paramount in being able to cut
You would also need a successively finer series of "grits" to finish
the stone. Rough grind with 100-200 grit (depending on the hardness
of the material), then finish sanding with 400-600, then 1200, and
maybe higher. Then polish with an appropriate compound. I still use
John Sinkankas as a reference.
I don't mean to discourage you. Save up, and buy the right
equipment! Shop around and keep your eyes open! You'll find what you
need if you put your "feelers" out!
All the best.
Sebaste Studio and
Carolina Artisans' Gallery
Charlotte, NC (USA)